Alpha-1-antitrypsin (AAT) is purified by an immunadsorbent technique in fully active form. The phenotypic variation is to be studied by attempting to raise in monkeys antisera which are specific for individual variants of the protein. The synthesis of AAT is being studied in established cell line of human hepatoma cells to determine molecular parameters involved in synthesis and excretion of AAT. BIBLIOGRAPHIC REFERENCES: Andrews, J.M., Rosen, F.S., Silverberg, S.J., Cory, M., Schneeberger, E.E., and Bing, D.H. (1977): Inhibition of C1s induced vascular leakage in guinea pigs by substituted benzamidine and pyridinium compounds. J. Immunol. 118:466. Donaldson, V.H., Rosen, F.S., and Bing, D.H. (1977): Role of the second component of complement and plasmin in kinin release in hereditary angioneurotic edema (HANE) plasma. Clinical Research. In press.